Tuesday, May 31, 2011

The Invasion of King Cane

Heard of the rabbit problem? Well… There’s more.

What is it? Cane Toads are large amphibians with large swellings behind each shoulder. They can be grey, yellowish, and olive or reddish-brown. They are normally about 15 cm long. The largest female cane toad was found in Queensland at a shocking 24 cm long. Cane toads are native to the southern United States and tropical South America. They were introduced to Australia in 1935 from Hawaii in order to control the scarab beetles. These beetles were pests of the sugar cane growing in Australia. They can be distinguished from the native Australian frogs as they sit upright and are active in the daytime and in dense clusters. Cane toads survive in habitats ranging from sand dunes to rainforests. They are the most abundant in open clearings and urban areas. They flourished in Queensland and most of the Northern Territory.

What’s the threat? Like many invasive species the cane toads soon became a problem. They have a wide array of toxins and chemical defenses present in almost all stages of their life cycle. The large glands on the back of the toads’ heads secrete the toxins. The toads will eat just about anything. When threatened, they will poison their predators and try to eat them. The population of many predators has declined. Unfortunately these predators are native to Australia. Native quolls, snakes, goannas and freshwater crocodiles may and have been lethally poisoned. Some species are predicted to adapt and learn to stay away from the toads, but it is unknown at what cost or if the species will even recover. For example the Northern quoll is now considered critically endangered. A major concern is the risk of children and pets being poisoned from contact with the toads, especially because the toads inhabit local areas.

Goannas are affected by the invasive toads -->

What to do? CSIRO has conducted research on the toads. They researched specific pathogens and tried to create a genetically modified virus to infect the toads with to help control the population. The project was shut down due to technical issues and lack of support of a genetically engineered virus. They’ve switched gears and have begun researching in other areas. There is a Cane Toad Advisory Group that offers advice and monitors the spread of the species. There are many other groups similar to this as well. Manual removal of the toads has become popular in highly populated areas and areas of important biodiversity.

What about here? The United States also has had problems with invasive species. The Asian carp has infected the Mississippi River and is traveling upstream headed for Lake Michigan. It is believed that the fish escaped into the river. Whatever the means, the invasive species is growing in population by the hour. The carp consumes about 40 percent of its body weight in plankton daily. This starves out the less aggressive species. As more native species die out due to the Asian carps’ feeding habits, the problem grows. The carps are endangering the biodiversity and wildlife in the Mississippi River. The public is afraid the situation will spread to all of the Great Lakes. If this were to happen the area would lose $7 billion in the fishing enterprise.

What did they do? One thing that has been attempted to stop the progression of the Asian carp was the creation of the electric devices. The U.S. Army Corps placed the devices in the waterway south of Chicago (links the Mississippi River to Lake Michigan) in 2002. The intention was to stop the carp by emitting electrical pulses at the water. Even though they replaced this system with an advanced one later on, scientists have still found DNA traces of the Asian carp on the other side of the system. The U.S. Environmental Protection Agency has stated their intensions to keep fighting the invasive species and keep the carp out of the Great Lakes.

Should we be concerned? Invasive species are something the world needs to be concerned with because they can severally impact and even destroy a native species. The iconic animals that are native to specific countries are destroyed as a result of these invaders. The invasive species affect the ecosystem often in negative ways. This can be seen in the situations in Australia and the United States. Humans affect the environment argumentatively too much; we should not affect nature any more than necessary.